The present invention pertains to torque sensors for automatic transmissions, and, more particularly, to the packaging of torque sensors near drive plate disks of dual clutch automatic transmissions.
An automatic transmission of a vehicle generally includes an input shaft and an output shaft. The input shaft receives an input torque from a power source, such as an internal combustion engine or an electric motor. The transmission then converts the input torque to an output torque. The output shaft transmits the output torque to the wheels of the vehicle in order to propel the vehicle.
The transmission typically converts the input torque to the output torque by adjusting a gear ratio (for example, during an upshift or a downshift) between the input shaft and the output shaft. This adjustment is accomplished by applying or releasing friction elements, such as clutches or brakes, in order to change torque relationships by altering planetary gear configurations of the transmission. Alternatively, in a transmission having one or more layshafts, the gears associated with the layshafts are used to change torque relationships. As a result, power flow paths are established and disestablished from the engine to the wheels.
The friction elements must be properly controlled in order to satisfactorily shift the transmission. To this end, information regarding the operation of the engine and transmission is generally used to control the friction elements. Typically, some of this information is estimated rather than directly measured. Direct measurement is preferred because it is more accurate. However, it is often more difficult to obtain direct measurements due to size constraints and other factors.
In the context of a dual-clutch automatic transmission, direct measurement of the operation of the engine and transmission is beneficial because accurate clutch slip control, through coordinated engine torque and clutch capacity control, is required in order to minimize drivability and noise, vibration and harshness (NVH) issues. In particular, a direct measurement of torque would be beneficial at a drive plate of the dual-clutch transmission in order to better understand engine and clutch torque relationships during a vehicle launch or gear shift. A direct measurement of torque can also improve clutch control by reducing hysteresis and temperature effects and increasing the accuracy of a clutch transfer function in terms of torque-to-actuator position.
Based on the above, there exists a need in the art for a way to directly measure torque at a drive plate of a dual-clutch automatic transmission.